Anne Zieger is veteran healthcare consultant and analyst with 20 years of industry experience. Zieger formerly served as editor-in-chief of FierceHealthcare.com and her commentaries have appeared in dozens of international business publications, including Forbes, Business Week and Information Week. She has also contributed content to hundreds of healthcare and health IT organizations, including several Fortune 500 companies. Contact her at @ziegerhealth on Twitter or visit her site at Zieger Healthcare.

When Progressive Insurance began giving car owners the option of having their driving tracked in exchange for potential auto insurance discounts, nobody seemed to raise a fuss. After all, the program was voluntary, and nobody wants to pay more than they have to for coverage.

Do the same principles apply to healthcare? We may find out. According to a study by digital health research firm Parks Associates, at least some users are willing to make the same tradeoff. HIT Consultantreports that nearly half (42%) of digital pedometer users would be willing to share their personal data in exchange for a health insurance discount.

Consumer willingness to trade data for discounts varied by device, but didn’t fall to zero. For example, 35% of smart watch owners would trade their health data for health insurance discounts, while 26% of those with sleep-quality monitors would do so.

While the HIT Consultant story doesn’t dig into the profile of users who were prepared to sell their personal health data today — which is how I’d describe a data-for-discount scheme — I’d submit that they are, in short, pretty sharp.

Why do I say this? Because as things stand, at least, health insurers would get less than they were paying for unless the discount was paltry. (As the linked blog item notes, upstart health insurer Oscar Insurance already gives away free Misfit wearables. To date, though, it’s not clear from the write-up whether Oscar can quantify what benefit it gets from the giveaway.)

As wearables and health apps mature, however, consumers may end up compromising themselves if they give up personal health data freely. After all, if health insurance begins to look like car insurance, health plans could push up premiums every time they make a health “mistake” (such as overeating at a birthday dinner or staying up all night watching old movies). Moreoever, as such data gets absorbed into EMRs, then cross-linked with claims, health plans’ ability to punish you with actuarial tables could skyrocket.

In fact, if consumers permit health plans to keep too close a watch on them, it could give the health plans the ability to effectively engage in post-contract medical underwriting. This is an unwelcome prospect which could lead to court battles given the ACA’s ban on such activities.

Also, once health plans have the personal data, it’s not clear what they would do with it. I am not a lawyer, but it seems to me that health plans would have significant legal latitude in using freely given data, and might even be seen to sell that data in the aggregate to pharmas. Or they might pass it to their parent company’s life or auto divisions, which could potentially use the data to make coverage decisions.

Ultimately, I’d argue that unless the laws are changed to protect consumers who do so, selling personal health data to get lower insurance premiums is a very risky decision. The short-term benefit is unlikely to be enough to offset very real long-term consequences. Once you’ve compromised your privacy, you seldom get it back.